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rrcthee 07-14-2010 03:39 PM

insulation in cape cod "semi vented" attic
Hi All,

I live in north central Ohio, and have a cape cod style roof, 1 1/2 story structure.

I purchased the home with the upstairs unfinished, currently it is like an attic, with cellulose insulation in the floor. It has eave vents, and some other vents (not ridge) along the top of the roof in the rear. It has already been framed with knee walls and a lowered ceiling in the middle (typical cape cod design).

The house has no soffit vents whatsoever, and a very narrow soffit to even consider trying to install vents into.

Here's my question... Could I dense-pack (cellulose) the roof all the way from the soffit to the ceiling of the of the framed-in room (like a cathedral ceiling), and then leave the space above the ceiling to be vented with the eave/roof vents? I've seen where dense pack can be used in a cathedral ceiling application with successful results.

I like the idea of using dense pack cellulose because it has good air/vapor barrier qualities. But, what if moisture develops behind the knee wall? Since this is techinically "inside the house" do I need to be concerned at all?


Should I just insulate the enclosed living space, leaving the area behind the knee wall "outside the house." I could do this by leaving air space above the slant walls...

This method provides traditional ventilation, but concerns me because the slant walls are 2X6's and will not leave much room for air circulation and an effective r-value using fiberglass. Furthermore, if I tried to add soffit vents, which I don't know if i even can, then I will have to combat the inherent air leak/draft issues which occur with this type knee wall setup.

Any thoughts or advice would be greatly appreciated!

Ron6519 07-15-2010 10:05 AM

If soffit vents are not possible there's a venting product that gets inegrated into the roof, down near the gutters that allows air to get into the interior and up the rafter bays to the ridge vent. If you need to, install a ridge vent to complete the system. I guarranty the venting system you currently have is inadequate.
As for the insulation, I would install it in the floor behind the knee wall, up the knee wall and around the living space. There's a picture on every insulation companies web site. I'm sure someone here will pop up a graphic. Don't forget the air space above the insulation so the air flow gets to the ridge.

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